Glossary Archive

A measure used in satellite navigation systems, such as GPS, to quantify the effect of errors in the timing of satellite signals on the accuracy of position calculations. It represents how much the timing errors in the satellite signals dilute the overall precision of the position solution. A lower TDOP value indicates better timing accuracy...

Small strips of lightweight material, such as yarn or ribbon, attached to a sail or rigging to indicate airflow and help sailors optimise sail trim and performance. Tell-tales are an essential tool for sailors, providing visual feedback on the airflow over a sail's surface. Typically made from lightweight materials like yarn, ribbon, or even thin...

A small boat used to transport people or goods between a larger vessel and the shore or another vessel.  A tender is an essential component of maritime operations, particularly for larger vessels that cannot dock directly at a pier or shallow waters due to their size or draught. Tenders are typically smaller, versatile boats designed...

The RYA Tender Operator course is tailored for individuals using tenders in marina or superyacht environments. The course covers low-speed handling, passenger safety, and maneuvering in confined spaces. Participants also learn about navigation, weather considerations, and effective communication with crew and passengers. By the end, participants will have the skills and confidence to operate tenders...

Sea area of the Met Office Shipping Forecast. Covers waters off southeast England, centered on the Thames Estuary. From the River Thames (“Tamesis,” “dark river”), Thames is relatively sheltered, with southwest winds of Force 3–5 and moderate seas, but vulnerable to severe storm surges. The 1928 Thames flood, following a storm surge, caused over 300...

"The bitter end" is a nautical term referring to the very end of a rope or chain secured to a ship or boat. Its name is derived from the sturdy post to which it was secured called the 'bitts post'.In modern language, It is sometimes used metaphorically to describe a situation in which one has...

The Challenger of Record is the yacht club or team officially representing the first challenging team in a sailing competition, such as the America's Cup. The Challenger of Record works closely with the defender (the current titleholder) to organise the event, negotiate the rules, and ensure fair competition. They play a crucial role in shaping...

An internationally renowned professional institution representing naval architects and marine engineers worldwide. It was founded in 1860 and is based in London, United Kingdom. RINA provides professional accreditation, training, and technical support to individuals and organisations involved in the design, construction, and operation of ships and marine structures. The institution plays a key role in...

Substitute or repeater flags allow messages with duplicate characters to be signalled without requiring multiple sets of flags.

The phrase “three sheets to the wind” comes straight from nautical life—and originally had nothing to do with drinking at all! 🚢 Nautical Origin: In sailing, a “sheet” is not a sail—it’s a rope (or line) used to control a sail’s angle to the wind. If a sailboat had one sheet loose, it would flap a bit. With two, it would...